[PATCH RESEND] riscv: don't specify -mno-save-restore when building with clang

[Palmer Dabbelt]

On Tue, 28 Jul 2020 06:12:52 PDT (-0700), tklauser at distanz.ch wrote:
> Clang doesn't support -msave-restore and -mno-save-restore. This avoids
> the following message emitted by clang:
>
>   '-save-restore' is not a recognized feature for this target (ignoring feature)
>
> Signed-off-by: Tobias Klauser <tklauser at distanz.ch>
> ---
> Resent due to infradead.org mailing list issues.
>
>  arch/riscv/Makefile | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
> index fb6e37db836d..cd3720bc45e8 100644
> --- a/arch/riscv/Makefile
> +++ b/arch/riscv/Makefile
> @@ -44,7 +44,9 @@ riscv-march-$(CONFIG_RISCV_ISA_C)	:= $(riscv-march-y)c
>  KBUILD_CFLAGS += -march=$(subst fd,,$(riscv-march-y))
>  KBUILD_AFLAGS += -march=$(riscv-march-y)
>
> +ifndef CONFIG_CC_IS_CLANG
>  KBUILD_CFLAGS += -mno-save-restore
> +endif
>  KBUILD_CFLAGS += -DCONFIG_PAGE_OFFSET=$(CONFIG_PAGE_OFFSET)
>
>  ifeq ($(CONFIG_CMODEL_MEDLOW),y)

Thanks, this one didn't make it the first time.  Is there a reason we can't use
cc-option here?  IIRC that's what we use for the other compiler options that
may be unimplemented, and it has the advantage of avoiding encoding specific
compilers into the build system.